This invention relates generally to a metal deposition cell and more particularly to anode electrodes of the metal deposition cell which have corrugated sides. The anodes and processes described herein are illustrated primarily in the context of an electroforming process, but the anodes are useful for other metal deposition processes including electroplating. The resulting electroformed articles are used for example as substrates in the fabrication of photoreceptors.
In electroforming cells employing two straight sided anodes, it is known that a mandrel moving through the channel defined by the anodes will experience varying current densities. The mandrel surface will experience varying current densities even if the mandrel were rotating. Non-uniform current densities tend to degrade the uniformity of the electroform thickness as well as the surface appearance of the electroform. The conventional response to the problem of varying current densities resulting from the use of straight sided anodes is to employ larger electroforming tanks to increase the mandrel to anode distance. However, the use of larger electroforming tanks requires more floor space, a larger quantity of bath components, and a higher voltage. There is therefore a need for a new anode design that allows the metal deposition process to occur at a smaller mandrel to anode distance which would decrease the size of the electroforming tank or apparatus. A smaller tank or cell reduces the amount of floor space, bath components, and/or voltage needed.
Various anode configurations and processes which employ these anodes are known:
Ashcroft, U.S. Pat. No. 1,545,383, discloses an electrolysis cell useful in connection with a process for the production of either zinc or lead by the reduction of the appropriate metal chloride. The anode and cathode surfaces of the electrodes of the cell may be corrugated to facilitate the flows of metal and chlorine in the cell. (See, e.g., page 3, lines 49-54).
Bailey et al., U.S. Pat. No. 3,844,906, discloses a process for maintaining a continuous and stable aqueous nickel sulfamate electroforming solution which employs an anode electrode in the form of an annular shaped basket.
Polan, U.S. Pat. No. 4,529,486, disclosed an arcuate shaped anode useful for the continuous electroforming of metal foil.